The present invention relates in general to hydrocarbon gasification, and more particularly to a hydrocarbon gasification system utilizing solar energy. The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.
The United States has a vast energy resource in the form of coal. The energy can be released from the coal through conventional power plant technology, wherein the coal is burned to produce steam and the steam is in turn used to produce electricity. It is also possible to produce a synthetic gas from coal that can be used in place of natural gas. It is, however, important to note that projected energy shortages for the United States over the near term appear to be for liquid fuels, particularly liquid fuels for powering automobiles and other forms of transportation. A system that would utilize hydrocarbons such as the vast coal deposits for the economical production of liquid fuels would be an important contribution to solutions to energy problems facing the United States.
Preliminary research has demonstrated the potential for utilizing solar energy to gasify coal and/or other carbonaceous matter such as hydrocarbons or biomass. Conventional gasifiers burn part of the coal to provide the heat required to drive the gasification reactions. A solar gasifier uses focused sunlight to provide this heat, which incorporates a renewable energy source in the gasification process. In addition, a substantial fraction of the solar energy is converted into chemical energy in the process, and the converted energy is stored in the product. Since solar energy is used rather than burning part of the coal to provide energy, less coal is required which conserves that resource and reduces potential environmental problems associated with the use of coal proportionately.
Solar coal gasification systems have been proposed, but all such systems would produce a combination of gases in the product stream. The combinations of gases typically include gases containing hydrocarbons, such as methane. Such hydrocarbon-containing product streams would be highly useful for pipeline quality gas, but would require expensive refining to produce liquid fuels suitable for powering motor vehicles. It is desirable to provide a system for gasifying coal, other hydrocarbons, and/or biomass, and produce a product stream that is free from hydrocarbons.